Of the known keyboards, in particular, that of the typewriter is to be emphasized. According to the arrangement of the letters on the upper left row of letters, this area is called in the English language the QWERTY-keyboard, in the computer language the ASCII keyboard (hereinafter either QWERTZ or ASCII keyboard). Especially advantageous is the inputting (typing-in or striking) according to the ten-finger system, which can be executed by the experienced typist without eye contact to the keys. It is also advantageous that the QWERTZ keyboard is a matter of a world-wide standardized keyboard, which is economically accessible. The disadvantage of the QWERTZ keyboard is that it is relatively voluminous and requires a fixed support surface. Furthermore, its use is associated with a relatively high physical exertion. This keyboard is regarded in the meantime as so far matured that its efficiency can now be only slightly further improved.
Further, keyboards are known with which for every stroke two sequential steps are required: First of all, the sensor present on the particular key must be touched. The proper input then occurs by thumb pressure on a central input key. It is disadvantageous, further, that to reach the sensor there are necessary lateral movements of the fingers, for which there are not favorable natural predispositions.
Also with the one-hand keyboard described in U.S. Pat. No. 4,042,777, a chord stroke (Akkordanschlag) is possible, in which the index, middle and ring finger(s) are used. On two full and two half rows of keys there are represented three rows of letters with the whole alphabet. While the upper and lower row, as seen from the operator, have nine letters, the middle one has eight. With this keyboard, the key spacings of the unshortened keyboard are very severely compressed in the rows, in order to make it possible to use the keyboard with one hand. Ten keys consist of one unit of their own, thirteen of two key halves each and three 0f four key quarters. What is disadvantageous is that the number of strokes to be executed by one finger is very high and the fingers frequently have to be spread and moved laterally. A reduction of the number of keys on the keyboard surface is not provided.
From U.S. Pat. No. 4,849,732 there is known a keyboard with which for each finger there is provided a multifunction key. Depending on the place of the stroke, there are different character (Zeichen) which can be generated. With such a known device, however, it is disadvantageous that it is only after the stroke that a possible wrong operation can be recognized. If, for example, such a keyboard is provided as a computer input device, then the user can detect the wrong input only by the appearance of the wrong character on the picture screen, and he has to correct it in a complicated manner.